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In vivo and ex vivo magnetic resonance imaging data. A listing of scanners and protocols is available here.
In-vivo brain MRI data are collected through the RADC cohort studies and substudies. Participants are imaged biennially using a number of pulse sequences providing structural, functional, and chemical information about the brain. The raw data are processed locally. Raw and processed data are made available for research inside and outside of the RADC. Raw data are made available "as is", but all processed data have passed our quality checks. We use a 3-step quality control strategy testing: 1) MRI scanner performance on a phantom, 2) quality of raw MRI data collected on humans, and 3) quality of information derived from processing. Each step involves thorough tests tailored to each MRI processing output as well as visual inspection.
Raw data is collected with the following sequences:
(Note: The above are sequences used on the 3T scanners. Similar sequences were run on the older 1.5T scanner. See protocols for exact description of the sequences.)
Processing of the raw MR images generates the following output (click on each type of output for more information on the methods used):
Regional gray matter volumes generated by the multi-atlas segmentation pipeline (MAS_ROI_**M)
Gray matter is first segmented and then divided into regions based on multi-atlas segmentation. The volumes of homologous regions in contralateral hemispheres are averaged. The average volumes are then divided by the intracranial volume and the ratio is multiplied by 1000. To find the name of the region corresponding to each variable name use the lookup table for the gray matter nodes of the IIT white matter atlas (www.nitrc.org/projects/iit ). Note: There are 3 variables which refer to combinations of two regions. These are MAS_ROI_05_15M: entorhinal and parahippocampal; MAS_ROI_26_31M: frontal pole and rostral middle frontal; and MAS_ROI_29_32M: temporal pole and superior temporal.
Median R2 values for gray matter regions segmented by the multi-atlas segmentation pipeline (R2med_ROI_**)
R2 values (i.e. 1/T2 values) for gray matter regions segmented by the multi-atlas segmentation pipeline. For each region, the R2 values from all voxels of the region in both the left and right hemisphere are grouped together and their median value is identified. The R2 values have units ms-1. To find the name of the region corresponding to each variable name use the lookup table for the gray matter nodes of the IIT white matter atlas (www.nitrc.org/projects/iit ). Note 1: There are 3 variables which refer to combinations of two regions. These are MAS_ROI_05_15M: entorhinal and parahippocampal; MAS_ROI_26_31M: frontal pole and rostral middle frontal; and MAS_ROI_29_32M: temporal pole and superior temporal. Note 2: The mean of the medians of all cortical regions and the mean of the medians of all subcortical regions are also provided.
Regional cortical thickness generated by Freesurfer (THK_ROI_**M)
The thicknesses of homologous regions in contralateral hemispheres are averaged. To find the name of the region corresponding to each variable name use the lookup table for the gray matter nodes of the IIT white matter atlas (www.nitrc.org/projects/iit ).
Reference: Fleischman DA, Leurgans S, Arfanakis K, Arvanitakis Z, Barnes LL, Boyle PA, Han SD, Bennett DA. Gray-matter macrostructure in cognitively healthy older persons: associations with age and cognition. Brain Struct Funct. 2014 Nov;219(6):2029-49. doi: 10.1007/s00429-013-0622-7. Epub 2013 Aug 17. PMID: 23955313; PMCID: PMC3926914
Regional gray matter volumes generated by Freesurfer (VOLG_ROI_**M)
The volumes of homologous regions in contralateral hemispheres are averaged. The average volumes are then divided by the intracranial volume and the ratio is finally multiplied by 1000. To find the name of the region corresponding to each variable name use the lookup table for the gray matter nodes of the IIT white matter atlas (www.nitrc.org/projects/iit ).
ARTS score | Arteriolosclerosis biomarker score |
---|---|
Brain age | Estimated brain age based on structural brain MRI data |
Cerebrospinal fluid volume | Cerebrospinal fluid volume - percent of intracranial volume |
Cortical thickness (AD signature) | Cortical thickness for the Alzheimer's disease signature |
Gray matter volume | Gray matter volume - percent of intracranial volume |
Intracranial volume | Intracranial volume (mm<sup>3</sup>) |
White matter hyperintensities volume | Log10 of percent intracranial volume occupied by white matter hyperintensities |
White matter volume | White matter volume - percent of intracranial volume |
Documentation in progress.